Remote adjustment of print settings

ABSTRACT

Systems and methods for providing remote approval of an image for printing are provided. One system includes a processing circuit in communication with an image capturing device that is configured to capture an image of a printed product. The processing circuit is configured to process the captured image into a processed image accurate to within a tolerance in a color space to indicate the visual appearance of one or more colors. The color space is a standardized color space, such as sRGB or CIELAB. The processing circuit is further configured to transmit the processed image to a display located remote from the image capturing device and to receive an input signal from a remote input device to allow a user to approve or reject the displayed processed image for printing on a print device.

RELATED APPLICATION DATA

The present application is a continuation of U.S. application Ser. No.14/707,987, filed May 8, 2015, which is a continuation of U.S.application Ser. No. 13/860,454 (now U.S. Pat. No. 9,047,520), filedApr. 10, 2013, which is a continuation of U.S. application Ser. No.13/475,776 (now U.S. Pat. No. 8,437,041), filed May 18, 2012, which is acontinuation of U.S. application Ser. No. 13/109,907 (now U.S. Pat. No.8,194,283), filed May 17, 2011, which is a continuation of U.S.application Ser. No. 12/646,641 (now U.S. Pat. No. 7,969,613), filedDec. 23, 2009, which is a continuation of U.S. application Ser. No.11/686,830 (now U.S. Pat. No. 7,652,792), filed Mar. 15, 2007, whichclaims benefit of U.S. Provisional Application No. 60/782,794, filedMar. 15, 2006, all of which are incorporated herein by reference intheir entireties.

BACKGROUND

Large scale printing operations employ various types of print devices(e.g., web offset, rotogravure, flexographic, digital printing, inkjet,etc.) with each having its own advantages and drawbacks. However, oneproblem common to most print devices 205 is the problem of producingcolor images that match a desired color image. Variations in the make-upof the ink, the quantity of ink used, the environment within theprinting facility, the settings or wear of the print device 205, etc.all can affect the actual color of the printed product 206. In order toproduce printed product of the color desired, printers often go througha two-step proofing process.

In the first proofing process, an image (e.g., an image from a digitalcamera or a photograph) is provided to a printer for reproduction. Theprinter then produces a color image on a proofing device that is withinthe color space of the printing equipment to be used to print theprinted product 206. This produced color image is referred to as aproof. The proof is then sent to the print buyer for approval. Onceapproved, the printer adjusts the print device 205 that will perform theprinting operation in an effort to match the approved proof. Theadjustment of the print device may include, for example, creating ofdigital image files based on a profile of the print device, and themanufacture of a printing plate or a rotogravure cylinder.

The second proofing step occurs when the print device 205 is ready toprint the printed product 206. A sample 101 of the printed product isremoved from the print device 205 and is placed on an ink desk 100 suchas is illustrated for a web offset press in FIG. 1. The print buyer andthe press operator review the sample 101 and make adjustments to theprint device 205 based on the sample 101 of the printed product. In theexample of FIG. 1, a plurality of ink keys 102 facilitate theadjustment. Each key controls ink flow to one vertical band or region ofthe printed product 206. This process is repeated until the print buyeris satisfied that the printed product 206 matches the proof. In somecases, this process has to be repeated when different batches of ink orprint media are employed or when other factors that may affect theprinted product 206 are varied, in addition to the beginning of a printrun.

The time spent reviewing the printed product 206 and making adjustmentsto the print device 205 is time that the print device 205 cannot be usedto produce usable printed product 206. As such, it is desirable to makethe adjustment process go as quickly as possible to maximize the timethat the print device 205 can be used for productive printing.

SUMMARY

According to one exemplary embodiment, a system includes an imagecapturing device configured to capture an image of a printed product ona printing press and a processing circuit in communication with theimage capturing device. The processing circuit is configured to processthe captured image into a processed image accurate to within a tolerancein a color space to indicate the visual appearance of one or morecolors. The tolerance is not greater than 4 ΔE of a color on the printedproduct, and the color space is a sRGB or a CIELAB color space. Theprocessing circuit is further configured to transmit the processed imageto a display located remote from the image capturing device and toreceive an input signal from a remote input device indicating whether auser has approved or rejected the displayed processed image for printingon the printing press.

According to another exemplary embodiment, a method includes receivingan image of a printed product on a printing press from an imagecapturing device and processing the captured image into a processedimage accurate to within a tolerance in a color space to indicate thevisual appearance of one or more colors. The tolerance is not great than4 ΔE of a color on the printed product, and the color space is a sRGB ora CIELAB color space. The method further includes transmitting theprocessed image to a display located remote from the image capturingdevice and receiving an input signal from a remote input deviceindicating whether a user has approved or rejected the displayedprocessed image for printing on the printing press.

According to another exemplary embodiment, a system includes aprocessing circuit in communication with an image capturing device thatis configured to capture an image of a printed product. The processingcircuit is configured to process the captured image into a processedimage accurate to within a tolerance in a color space to indicate thevisual appearance of one or more colors. The color space is astandardized color space. The processing circuit is further configuredto transmit the processed image to a display located remote from theimage capturing device and to receive an input signal from a remoteinput device to allow a user to approve or reject the displayedprocessed image for printing on a print device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective schematic view of a prior art ink desk;

FIG. 2 is a perspective schematic view of a prior art color bar controlsystem for a print device;

FIG. 3 is a prior art flow chart illustrating the operation of the colorimage control system of FIG. 2;

FIG. 4 is a flow chart illustrating operation of a print deviceincluding a color control system and a virtual ink desk embodying theinvention;

FIG. 4a is a perspective schematic view of the print device and virtualink desk of FIG. 4;

FIG. 4b is a flow chart illustrating operation of the print deviceincluding the color control system and the virtual ink desk;

FIG. 5 is a schematic illustration of an image capturing deviceconfigured for use with the virtual ink desk of FIG. 4;

FIG. 6 is a schematic illustration of an illumination device suitablefor use with the image capturing device of FIG. 5;

FIG. 7 is a view of a user interface screen of the virtual ink desk ofFIG. 4;

FIG. 8 is a view of another user interface screen of the virtual inkdesk of FIG. 4;

FIG. 9 is a flow chart illustrating operation of a print deviceincluding a color control system and a virtual ink desk embodying theinvention;

FIG. 10 is a schematic illustration of a printed web illustrating animage capture arrangement;

FIG. 11 is a schematic illustration of a portion of the image capturingdevice of FIG. 5;

FIG. 12 is a flow chart illustrating operation of a print deviceincluding a color control system and a virtual ink desk embodying theinvention;

FIG. 13 is a view of another user interface screen of the virtual inkdesk of FIG. 4 showing a selected region of interest;

FIG. 14 is a view of another user interface screen of the virtual inkdesk of FIG. 4 that shows the color adjustment controls for makingchanges in the L*a*b* color space;

FIG. 15 is a view of another user interface screen of the virtual inkdesk of FIG. 4 that shows the color adjustment controls for makingchanges using CMYK density;

FIG. 16 is a view of another user interface screen of the virtual inkdesk of FIG. 4 that shows a blobular inline conflict/color shift tool;

FIG. 16a is a view of another user interface screen of the virtual inkdesk of FIG. 4 that shows the blobular inline conflict/color shift tool;

FIG. 17 is a view of another user interface screen of the virtual inkdesk of FIG. 4 that shows the selection of a region of interest from asecond application such as ADOBE PHOTOSHOP;

FIG. 18 is a flow chart illustrating one possible disadumbrationprocess;

FIG. 19 is a side schematic view of a portion of a printing press; and

FIG. 20 is a schematic sensor array circuitry system diagram.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. The use of“including,” “comprising,” or “having” and variations thereof herein ismeant to encompass the items listed thereafter and equivalents thereofas well as additional items. Unless specified or limited otherwise, theterms “mounted,” “connected,” “supported,” and “coupled” and variationsthereof are used broadly and encompass direct and indirect mountings,connections, supports, and couplings. Further, “connected” and “coupled”are not restricted to physical or mechanical connections or couplings.

In order to maintain the color of the printed product 206 at the desiredlevels, a color image control system 300 is often employed. Color imagecontrol systems 300 such as the one illustrated in FIG. 3, and employedin the constructions of FIGS. 4b and 12 are known. These systems use animage scanner 301 to capture an image 302 of the printed product 206.This image 302 is then compared to a target image 303 at block 304. Inthe construction of FIG. 3, the scanned image 302 is passed to an imagecompare module 304 a. This module first aligns the scanned image 302 tothe target image 303. The target image 303 is preferably derived fromdigital images used to create the printing plates, but may be derivedfrom the printing plates themselves, or may be derived from a proof.Once color of the printed web has been deemed acceptable, a scannedimage 302 or an adjusted image may become the target image 303.

Alignment is performed through correlation techniques that are wellknown. With the technique of correlation, the correspondence betweenpixels in the two images has been established so that pixel color valuescan be compared at substantially the same pixel locations of the targetimage 303 and the scanned image 302.

Alternate pattern matching techniques may be used to establish alignmentbetween the images. Fiducial marks may be employed, as with registercontrol systems commonly used on printing presses. Alternately,mechanical means may be used to ensure that the two images are inalignment. In this case, the comparison module 304 a may not require analignment step.

After alignment, comparison is made between the scanned image 302 andthe target image 303. This comparison may, for example, be a subtractionof one set of color values from the other. The results of thecomparison, desired color changes for each pixel, are then passed to aprocessing module 306, 306 a which makes use of a sensitivity matrix 305and regression techniques to determine the set of color adjustments thatwould bring the scanned image 302 into closest agreement with the targetimage 303.

The processing module 306 works in the following manner. For each pixeland each color channel (X, Y, and Z, or L*, a*, and b*, for example),the sensitivity matrix 305 provides an estimate of the amount of colorchange that would occur in the scanned image 302 if a unit change ismade to one of the ink key openings 207. The sensitivity matrix has anentry for each combination of color channel, pixel in the image and inkkey.

For a given 1.28 inch strip of the printed web 206, the scanned imagemay be 128 pixels wide by 6000 pixels tall. The color for this width maybe directly controlled by three sets of ink keys, for example. Due tothe spread of ink from a single ink key, there may be seven sets of inkkeys that are taken into consideration. Each set of ink keys may includefor example, cyan, magenta, yellow, black, as well as any custom inks.

A strip may be 128×6000 pixels. Thus, the number of sensitivity matrixentries for a strip is 3×4×128×6000 or ˜9 million entries. A largeprinting plate may be 120″×60″. At 100 DPI, the sensitivity matrix of asingle surface of this size would be 864 million entries. As theseentries would likely be stored using floating point numbers, we couldexpect the sensitivity matrix for this plate to use 3,296 megabytes ofmemory.

Given these entries in the sensitivity matrix 305, it is thereforepossible to generate a set of linear equations relating changes in inkkey openings to the desired color changes for each pixel. This set oflinear equations can then be solved by regression techniques todetermine the set of ink key openings 207 that best reaches the desiredcolor changes. The resulting changes in ink key openings will then becombined with the ink key openings 207 that were being used when thescanned image 302 was printed.

Alternately, the set of equations may be nonlinear. The use of the wordregression is not meant to imply a single algorithm for theminimization. Singular value decomposition, nonlinear regression, orLevenberg-Marquardt algorithms may be beneficially used.

For some print jobs, there are portions of the work that are morecritical for color than others. Within a print job, the color accuracyof editorial content may be less critical than the color accuracy of anadvertisement. Within a picture in an advertisement for example, thereare degrees of criticality. The shade of the ground in a picture may forexample be the least critical. Flesh tones and blue sky, being so-calledmemory colors, are generally more critical. The color of the product inthe advertisement is typically the most critical in terms of coloraccuracy.

To accommodate the need for different levels of criticality, it ispossible to use weighted linear regression so that areas of criticalcolor have, in effect, a lower tolerance for color discrepancies.

The sensitivity matrix 305 is derived from the images used to producethe printing plates. The sensitivity matrix and the derivation thereofare described in detail in U.S. Pat. No. 5,967,050, which is fullyincorporated herein by reference.

The processing module 306 a hence generates a set of ink key openings207 that will cause the printed web 206 to come closest to matching thetarget image 303. The printing press 205 will be commanded to move theink keys to the desired ink key openings 207, and, after a suitabledelay, a new scanned image 302 is collected and the process repeats. Thedelay is required to allow any inking changes to propagate through theprinting press 205. A tuned PID loop may be used to reduce the requireddelay.

In the preferred embodiment, the color image control system 300described in FIG. 3 may beneficially be used in conjunction with acolorbar control system 200, as is indicated in FIG. 12.

The virtual ink desk 400 will in this way perform the function of animage color control system 300 during the makeready phase, and alsoduring the production phase. During the color OK phase, a traditionalimage color control system 300 is typically disabled so that the pressoperator can make changes. As will be seen, the virtual ink desk 400 hasthe advantage of being able to maintain control of color during thecolor OK phase.

FIG. 4b schematically illustrates a virtual ink desk 400 embodying theinvention. The virtual ink desk 400 is shown and discussed herein inconjunction with a print device 205 and particularly with a web offsetprinting device. Of course, the virtual ink desk 400 described hereincould be used with many different printing devices but is best suitedfor use with high-speed printing devices including but not limited toweb off set presses, rotogravure, flexographic printing, sheetfedprinting, high-speed digital printing systems, and the like. The virtualink desk 400 is particularly advantageous with these high-speed printdevices 205 as the virtual ink desk 400 can greatly reduce themake-ready period for a print job, thereby reducing wasted time as wellas wasted resources (e.g., ink, print media, etc.).

The print device 205 receives a print media such as a web and dischargesa printed product 206 that includes a printed image. In preferredconstructions, the printed image is a color image. However, black andwhite or gray scale printing may also employ the virtual ink desk. Asone of ordinary skill in the art will realize, a small portion of theprint device 205 performs the actual printing operation with otherinterconnected portions performing additional operations such as dryingthe printed product 206, trimming, folding, aligning, stacking, and thelike.

The print device 205 typically includes one or more adjustable inkcontrol devices. These devices can be adjusted to vary the flow,quantity, pigment saturation, roller pressure or other ink parameters toallow for variation in the printed product. In color systems, at leastone ink control device is provided for each color of ink employed (e.g.,cyan, magenta, yellow, black, and custom colors). In most commercialsystems, multiple regions or bands are defined with each band includingone ink control device for each color.

For example, in a web offset printing system, a web passes through thevarious color print units in order for an image to be printed on theweb. A plurality of ink keys act as the ink control devices. The keyscan be adjusted to increase or decrease the quantity of a particularcolor of ink that is available to a particular region or band. However,as one of ordinary skill in the art will realize, adjusting one ink keyin one region or band can affect the adjacent bands. In addition,adjusting an ink key to change the color of a portion of a band (e.g.,the image of an automobile) will affect other regions within that band.

Generally, any print job includes at least three distinct phases. Thefirst phase is the proofing phase. In this phase, the printer works toproduce a printed image that matches an image that the print buyerwishes to have printed. Once an image is agreed upon, this image becomesthe proof image (sometimes referred to as proof and printed proof). Thenext phase is the makeready/color OK phase. In this phase, the pressoperator works with the print buyer to adjust the particular press orpresses being employed to assure that the actual printed imagessufficiently match the proof image. Finally, once the makeready phase iscomplete, the printing phase begins. During the printing phase, theshippable printed product is produced, and bound if desired for shipmentto the consumers.

During the makeready portion of a print run, an image scanner 301 viewsthe printed product 206 to create a scanned image 302. The imagecapturing device or image scanner 301 measures the color of the printedproduct 206 at a plurality of sampling locations.

The image scanner 301, shown schematically in FIG. 5, is designed tomeasure the color of the printed media 206 at a multiplicity ofpreferably adjacent locations. The size of these locations depends uponthe application, but may be, for example, 0.010 inch by 0.010 inch.Preferably, the measurement locations will cover substantially all ofthe saleable work 204.

The measurements may be reported in the CIELAB color space or in thesRGB color space, but may be in whatever color space best serves theapplication. In preferred constructions, the color space used is suchthat the captured image is color-correct.

Thus, the image scanner 301 will produce a scanned image of preferablythe entire saleable work 204 at a fine enough resolution and high enoughcolor fidelity so as to be useful for visual inspection.

For the purposes of this patent the term color-correct shall be taken tomean that measurements of color made with the image scanner 301 shall beaccurate to within a tolerance of a standard color space which isdesigned so as to predict the visual appearance of a color, such asCIELAB or CIELUV. The tolerance required is application dependent. Forweb offset printing, for example, where tolerances for printed colorsmay be 4 ΔE of target values (see ISO 12647-2), an acceptable accuracytolerance may be 2 ΔE. In particular, it should be noted thatmeasurements made with a typical flatbed image scanner, or color cameraare frequently not color-correct and are device dependent without theaid of a device profile. Even with a device profile, color correctnesswill often be media and pigment set dependent. The use of devicedependent color spaces, such as RGB or CMYK, are in general notcolor-correct without a device profile. On the other hand, images storedin a color space such as sRGB or CIELAB are generally color-correct.

As discussed, preferred systems combine the various images to produce asingle scanned image 302 of the entire repeating portion of the printedmedia 206.

The scanned image 302 is transmitted via a transceiver 440 ortransmitter (shown in FIG. 4a ) from the print device to a computer 438of the virtual ink desk 400 for further review and/or processing. Thecomputer includes a second transceiver 445 (shown in FIG. 4a ) thatreceives the scanned image 302 at the computer. Before proceeding, itshould be noted that the term “transmitted” should be interpretedbroadly to include virtually any system which delivers the capturedimage to the computer. As such, a wireless transmission, transmissionthrough a wired network, through a direct connection, via the Internet,or any other direct or indirect connection should be considered atransmission. In addition, the transceiver should be interpreted as anydevice capable of sending and/or receiving data, whether wirelessly, viaa wire, or using other means. Thus, a modem, an Ethernet card, and awireless transmitter should all be considered transceivers. In addition,transmitters or receivers, while only able to transmit or receive datarespectively, should also be considered transceivers.

As shown in FIG. 4a , the computer includes a video display or monitor404, a processor 455, an input device 460, a storage device 465 and thetransceiver or transmitter 445. The processor operates to display a userinterface on the video display. The user interface allows a user to workwith the various images that are presented. Before proceeding, it shouldbe noted that a user could include, without limitation, a customer, aprint owner, a press operator, a representative, etc. In oneconstruction, a touch screen is employed as the user interface. However,preferred constructions employ other input devices (e.g., mouse, puck,trackball, pen, etc.). Thus, the computer of FIG. 4a , contains orperforms most, if not all, of the items illustrated in FIG. 4. Ofcourse, other constructions may divide these items or steps among morethan one computer as desired.

The user interface uses the video display 404, which serves as a videodisplay device and may be, for example, a cathode ray tube, a liquidcrystal display, a projection device, a plasma display, or the like. Thevideo display 404 has preferably been calibrated so that it iscolorimetrically correct.

This scanned image may be transmitted to a colorbar control system 200(FIG. 2), which provides adjustments of the adjustable ink controldevices in order for the colorbar measurements to be within a toleranceof the target SID (solid ink density) values 1201.

Preferably, this scanned image 302 will be passed to a color imagecontrol system (CICS) 300. Such a system utilizes the saleable work 204,rather than the colorbar 203 alone to decide if and how adjustments toinking levels need to be made. The color image control system 300 mayact in consort with a colorbar control system 200 to effect theadjustments, or it may make the adjustments directly.

It is to be appreciated that the actions of a press operator may be usedto initially adjust the inking levels. Alternately, a preset system mayprovide this same functionality.

As a result of the actions of the color image control system 300 orother such mechanisms for the initial setting of the adjustable inkcontrol devices, the printed media 206 will match the printed proof tosome level. In practice, it is generally the case, however, that furtheradjustments of the ink control devices is necessary to bring the printedmedia 206 within an acceptable color match.

Thus, it is a common practice that a print buyer or print buyerrepresentative provide an initial approval, commonly known as a colorOK. Prior to color OK, printed product 206 may not be acceptable forshipping.

To perform a color OK in the prior art, the press operator operates theprint device 205 to generate printed product 206. A sample of theprinted product 206 is placed on an ink desk 100 or similar devicealongside the proof and adjustments are made. The print device 205 isagain operated and another sample of the printed product 206 is placedon the ink desk 100.

If the print device 205 is a web offset printing press, this press willbe continuously operating and generating waste during this time period.It is also necessary on a web-offset printing press to wait for anadjustment of the ink control devices to settle out before pullinganother sample.

This process repeats until the printed media 206 meets the approval ofthe print buyer, which may unfortunately require multiple iterations,thus creating copious waste.

The virtual ink desk 400 shortens the color OK process by displaying forthe press operator and the print buyer a prediction of what a givenadjustment to the ink control devices will look like. Tentative changescan thus be evaluated without the need of producing the waste on press.

The scanned image 302 is displayed on the video display 404, optionallyshown in split screen mode along with the target image 303. The pressoperator then enters tentative SID (solid ink density) changes 407through the color adjustment screen 1500.

The color adjustment screen 1500 as shown in FIG. 15 allows color movesthat include indirect adjustments of CMYK ink key openings 207. In thisuser interface 1500, bars with up and down adjustments 1501-1506 arepresented to allow the user to indirectly manipulate the CMYK colors forthe selected area. In addition, adjustments are provided for any custominks or colors that may be employed. In this user interface 1500, asmall image of the printed web is also displayed to show the regionbeing adjusted. The small image may be a portion of the target image 303or the scanned image 302, for example. In other constructions, directmanipulation of the ink keys may be facilitated by the virtual ink desk.

Specifically, as shown in FIG. 12, the prediction module 405 makeschanges to the scanned image 302 so as to predict the appearance of theprinted media 206 as if those tentative ink key openings 407 wereimplemented at the print device 205. Once the predicted image 402 hasbeen determined, this predicted image 402 will be displayed on the videodisplay 404. In this way, the user has immediate feedback as to how acontemplated color move may change the color of the selected area aswell as the color of the entire printed media 206. This will allow arelatively novice press operator to make intelligent decisions about howto adjust color.

If the predicted image 402 is not deemed a suitable match, the pressoperator may request additional color changes. This process continuesuntil the user has found a suitable match. At this time, the pressoperator issues a command to enact the requested changes. The tentativeSID changes 407 will be transferred to the target SID values 1201, andthe predicted image 402 will be transferred to the target image 303, sothat the colorbar control system 200 or the color image control system300 will revise its control so as to meet the revised target points.

Alternately, the tentative SID changes 407 will be transferred to thetarget SID values 1201 without transferring the corresponding predictedimage 402 to the target image 303. The colorbar control system 200 willthereafter be enabled until the measurements of the colorbar 203 havegotten to within a tolerance of the target SID values 1201 andoptionally when inking levels on the high-speed print device havesettled out. Thereafter, the following scanned image 302 will betransferred to the target image 303.

The prediction module 405 uses the scanned image 302 as a starting pointfrom which to estimate the effect that the tentative ink key openings407 would have on the image of the printed media 206, were these changesto be sent to the print device 205. To determine this estimation, theprediction module 405 utilizes the scanned image 302, the ink keyopenings 207 that were used to produce this printed media 206, thetentative ink key openings 407, and the sensitivity matrix 305.

A difference is computed between the ink key openings 207 that were usedto produce this printed media 206 and the tentative ink key openings407. This difference in ink key openings is multiplied by thesensitivity matrix 305 to estimate the amount of color change. The colorchange is then added to the scanned image 302 to arrive at the predictedimage 402.

The predicted image 402 can be determined from the scanned image 302,the tentative SID changes 407, and the sensitivity matrix 305 accordingto the following equation.

$\begin{bmatrix}{\Delta_{L^{*}}(1)} \\{\Delta_{a^{*}}(1)} \\{\Delta_{b^{*}}(1)} \\{\Delta_{L^{*}}(2)} \\{\Delta_{a^{*}}(2)} \\{\Delta_{b^{*}}(2)} \\\vdots \\{\Delta_{L^{*}}(n)} \\{\Delta_{a^{*}}(n)} \\{\Delta_{b^{*}}(n)}\end{bmatrix} = {\begin{bmatrix}{S_{L^{*},C}(1)} & {S_{L^{*},M}(1)} & {S_{L^{*},Y}(1)} & {S_{L^{*},K}(1)} \\{S_{a^{*},C}(1)} & {S_{a^{*},M}(1)} & {S_{a^{*},Y}(1)} & {S_{a^{*},K}(1)} \\{S_{b^{*},C}(1)} & {S_{b^{*},M}(1)} & {S_{b^{*},Y}(1)} & {S_{b^{*},K}(1)} \\{S_{L^{*},C}(2)} & {S_{L^{*},M}(2)} & {S_{L^{*},Y}(2)} & {S_{L^{*},K}(2)} \\{S_{a^{*},C}(2)} & {S_{a^{*},M}(2)} & {S_{a^{*},Y}(2)} & {S_{a^{*},K}(2)} \\{S_{b^{*},C}(2)} & {S_{b^{*},M}(2)} & {S_{b^{*},Y}(2)} & {S_{b^{*},K}(2)} \\\vdots & \vdots & \vdots & \vdots \\{S_{L^{*},C}(n)} & {S_{L^{*},M}(n)} & {S_{L^{*},Y}(n)} & {S_{L^{*},K}(n)} \\{S_{a^{*},C}(n)} & {S_{a^{*},M}(n)} & {S_{a^{*},Y}(n)} & {S_{a^{*},K}(n)} \\{S_{b^{*},C}(n)} & {S_{b^{*},M}(n)} & {S_{b^{*},Y}(n)} & {S_{b^{*},K}(n)}\end{bmatrix}\begin{bmatrix}\Delta_{C} \\\Delta_{M} \\\Delta_{Y} \\\Delta_{K}\end{bmatrix}}$

The variables are defined as follows

Δ_(C), Δ_(M), Δ_(Y), and Δ_(K) are the tentative SID changes 407 for thecyan, magenta, yellow and black inks,

S_(L*,C) (i) (for example) is the “sensitivity” of the L* value of thei^(th) pixel to a unit change in the cyan SID. A unit change in thesolid ink density of cyan will make this large of a change in the L*value, and

Δ_(L*)(i), Δ_(a*)(i), Δ_(b*)(i) are the resulting color differences forthe i^(th) pixel, i=1, 2, 3, . . . , n. These values are added to thecorresponding pixels of the scanned image 302 to produce the predictedimage 402.

In the foregoing section describing the calculation of the predictedimage 402, the scanned image has been used as the starting point fromwhich to make the predictions. Alternately, it may be beneficial tostart with the target image 303.

The virtual ink desk 400 may be beneficially employed to perform aremote color OK. Whereas today it is common for print buyers to send arepresentative to the printing plant for a color OK, it now becomespossible for this to be accomplished remotely.

It is known in the art to retrieve a portion of the printed product 206and scan this using a commercially available flatbed scanner. An ICCprofile is then used to convert the native RGB output of the flatbedscanner to CIELAB values so that a color-correct image of the printedproduct 206 may be displayed on a calibrated monitor at the printbuyer's location.

The time consuming step of profiling the flatbed scanner for each printcondition is obviated through the use of an image scanner 301 thatincorporates a spectrophotometer, or is otherwise color-correct, as infor example, the use of spectral response functions which are a linearcombination of the tristimulus functions. If the image scanner islocated so as to be able to scan the printed product 206 automatically,as in the preferred embodiment, a second time consuming step, that ofloading the printed product onto the flatbed scanner, is similarlyobviated.

The image scanner 301 captures a color-correct scanned image 302 of theprinted product 206 which is transmitted via the transceiver to avirtual ink desk 400. The virtual ink desk 400 may be located locally(i.e., in the same building or printing facility as the print device)and/or may be located remotely (i.e., in a different facility or city).The captured image is compared to the original proof to determine if thecolors match. This original proof may be a hardcopy (i.e., printed)proof, or it may be a digital representation of the proof, displayed ona computer monitor. Preferably, the original proof may be a display ofthe target image 303 on the video display 404. The virtual ink desk 400allows for a side-by-side comparison of the proof or target image andthe captured image. In addition, the images can be zoomed or panned toallow for a thorough inspection.

Adjustable ink control devices from a location remote from the press hasheretofore been limited by the need for the press operator to retrieve asample of the printed product 206 from the print device in order toascertain the required color changes. Thus, it has not been practical toadjust ink control devices from a distance of more than perhaps a fewhundred feet.

The virtual ink desk 400 as described herein may be operated remotely,which is to say, the operator may initiate ink control deviceadjustments from a press office, for example, located at some distancefrom the print device 205 itself. Additionally, the virtual ink desk 400could be located at the print buyer's facility in a different city ifdesired. The print buyer could make all of the adjustments necessary toadjust the image to a desired image and implement the ink key changes,thus reducing the role of the press operator. However, ideally, theexperienced press operator facilitates the adjustments and the printbuyer reviews and approves the results remotely.

The invention as described herein is one-to-one, i.e. there is onevirtual ink desk 400 controlling a single printing device 205. Thecurrent invention may benefit from being configured in a one-to-manymode. In a particularly advantageous embodiment of this invention, asingle virtual ink desk 400 may be configured so as to control both thebottom side and the top side of the printed media 206. This may beaccomplished, for example, by programming the system so as to togglebetween the two sides of the web. This principle applies equally well toa single virtual ink desk 400 controlling both webs of a two web press,or controlling more than two presses.

If a virtual ink desk 400 has access to image data from a number ofpresses, say for example, through a computer network, then it ispossible for a single virtual ink desk 400 to control a multiplicity ofprint devices 205. In this way, a single skilled press operator mayperform the color OK phase on many presses.

It is also possible for a multiplicity of virtual ink desks 400 tocontrol a single print device 205 (many-to-one). This may be useful, forexample, if one virtual ink desk 400 is located in the proximity of theprint device 205, a second virtual ink desk 400 is located in the pressoffice of the printing plant, and a third virtual ink desk 400 islocated at the site of the print buyer.

In a particularly advantageous embodiment of this many-to-oneconfiguration, the remote virtual ink desks 400 (those in, for example,the press office and at the print buyer site) have a subset of thefunctionality of the virtual ink desk 400 located at the press. Inparticular, the print buyer sites may only be allowed to view thescanned image 302 and the target image 303. This functionality allows aprint buyer to remotely approve of the color rendition. This saves theprint buyer the time and expense required to travel to the printingplant.

The previously described virtual ink desk 400 embodiment exemplified byFIG. 12 is one that most closely fits the current operation of a printdevice 205. For example, operators of web offset printing presses arefamiliar with the adjustment of ink keys in order to control the densityof ink within an ink key zone. Thus, the embodiment of FIG. 12 is mostefficacious for trained press operators.

Others less familiar with the operation of a print device 206 may findit advantageous to adjust color in a way that does not necessitate adetailed understanding of ink keys and of density.

In the preferred embodiment of the virtual ink desk 400, the pressoperator views the scanned image 302, possibly alongside the targetimage 303, and selects some area of the image wherein it is deemed thatcolor should be modified. The press operator then enters a contemplatedcolor change for the selected area.

The virtual ink desk 400 will then compute the tentative SID changes 407required to effect the contemplated color change for the selected area.Next, the prediction module 405 will determine the predicted image 402if those SID changes were to be sent to the print device 205. Thispredicted image 402 will be displayed on the video display 404 for thepress operator.

When a user (e.g., press operator, print buyer, supervisor, etc.)selects a selected area 702 for adjustment, the user interface 401 mustdetermine which pixels the user intends to be adjusted. The userinterface 401 will then provide feedback to the user as to which pixelshave been selected. This feedback may be done, for example, by flashingthe selected pixels, or by indicating the border of the selected pixelsby means of a dotted line or a flashing dotted line. This flashingdotted line has been nicknamed “marching ants” in the industry. In FIG.7, a dotted line is used to indicate the border of the selected area702, which in this case is the body of the car. In the preferredembodiment (FIG. 13), a border is used to indicate a portion of theimage that has been selected (1301 and 1302), along with reducing thesaturation of the rest of the image (i.e., graying out the rest of theimage).

There are a variety of methods that may be employed by the userinterface 401 in order to define the selected area 702. In the simplestimplementation, only the pixels directly indicated by the user interfaceare selected.

In a more sophisticated embodiment, the pixels directly selected by theuser interface (hereinafter referred to as “directly selected pixels”)are selected, as well as those pixels (indirectly selected pixels) thatare proximate to the directly selected pixels, and that have colorvalues similar to the directly selected pixels. To identify suchindirectly selected pixels, an iterative algorithm may be used.

In this iterative algorithm, the set of directly selected pixels becomethe initial set of selected pixels. The mean color value of this set iscomputed and any outliers are eliminated from the set of selectedpixels.

Next, any pixels directly adjacent to any of the selected pixels areexamined. If the color values of any of the examined pixels are within acertain tolerance of the mean color value of the selected pixels, thenthese pixels are added to the set of indirectly selected pixels. Thistolerance may be, for example, a predetermined ΔE. Thus, this systemwill select adjacent similarly colored pixels.

Alternately, the tolerance for acceptance may be a ΔE derived from thestatistical properties of the color values of the selected pixels. Forexample, the ΔE between the color values of each of the selected pixelsand the mean of the selected pixels is computed. The mean and standarddeviation of this set of ΔE values is computed and the upper thresholdtolerance might be taken, for example, as the mean ΔE plus three timesthe standard deviation of the ΔE values.

The mean and standard deviation of the set of selected pixels may becomputed over only the directly selected pixels, or it may includeindirectly selected pixels if desired.

This process of evaluating adjacent pixels and potentially adding themto the set of selected pixels is continued until there are no additionaladjacent pixels that should be added. The final set of selected pixelswill become the selected area 702.

This implementation may not work well for areas of an image where thecolor is slowly changing across the image as is typically the case for ashaded area of an image. It may be beneficial to modify the acceptancecriteria so that a pixel is added to the set of selected pixels if it isadjacent to a selected pixel and if the color value of the pixel iswithin a certain ΔE of the previously selected pixel. Equivalently, theset of selected pixels is grown in all directions until an edge isreached.

In this way, it is easy for the user to select all the pixels thatcorrespond to a specific object in the image, for example, a sweater ora car. Since objects with natural lighting tend to exhibit a range ofbrightness, but do not change significantly in hue or saturation, it isadvantageous to use a modification of the ΔE calculation that placesless emphasis on the difference in L* value by weighting the L*difference when a color difference is calculated.

It is also possible to restrict the growth of the set of selected pixelsto within an ink key zone 103, to within several ink keys zones, or towithin a page if desired.

It may be advantageous in some circumstances for a selected area 702 toencompass a variety of disjointed areas on the printed product 206.There may be, for example, a number of images of the same or similarobjects on the printed product 206. One common example of this is theletters of the title of a magazine. Such a title on the cover of amagazine often has tight requirements for color. To meet this need, theuser interface 401 may allow additional groups of pixels to be added tothe selected pixels when the user indicates another area of the image.Alternately, the user interface 401 may automatically search the entireimage, or entire page for color values that are within a certaintolerance of the color of the selected pixels.

In the preferred embodiment, the user traces with a mouse 460 or othersuitable pointing device an outline of those pixels that are to beselected, as shown in FIG. 13. The outline that is traced may be limitedto a simple geometric figure such as a rectangle or ellipse. The outlinemay alternately be an arbitrary polygonal figure that connects anordered set of image coordinates or a random curve that follows thepixels selected by the user. In still another embodiment, the outlinemay be a Bézier curve that smoothly traces through an ordered set ofimage coordinates. In still other constructions, other outline types orcombinations of those described may be employed. For any of the thusgenerated outlines, the outline may be taken directly, or the outlinemay be refined so as to occur at the nearest edges of the image. In thepreferred embodiment, the user interface 401 allows the user to selectamong these methods of specifying the selected area 702.

As discussed, this functionality may be arrived at, for example, byusing a suitable computer pointing device such as a mouse 460 ortrackball, or by typing image coordinates on a keyboard or throughrepeated use of arrow keys. Similar functionality could be attainedthrough an eyeball tracking device. Additionally, a touch screen may beemployed if desired, however, touchscreens utilized in a printingenvironment frequently become dusty and smeared with ink. This severelydetracts from the color fidelity of the monitor.

Once the selected area 702 has been determined, the user interface 401presents the user with a color adjustment screen 1400 for themodification of the color of the selected area 702. Preferably, thecolor changes that are available to the user through the user interfaceinclude: a change in hue, in saturation, or in brightness. Examples ofpotential user interface screens are illustrated in FIGS. 8, 14 and 15.

FIG. 14 illustrates the preferred embodiment color adjustment screen1400 that includes a color wheel 1411 that facilitates the coloradjustment for the selected pixels or region. The user interface screen1400 of FIG. 14 is similar to the one of FIG. 15, with the exception ofthe color control mechanism. The center of the circle represents thecurrent color, thereby allowing a user to simply selects an arrow1401-1406 on the outer periphery of the wheel 1411 to increase the colorin that direction. The gray bar 1407 to the right of the color wheel1411 can be used to increase or decrease the lightness of the color. Thearrows 1401 through 1406 allow adjustments in the Yellow, Red, Magenta,Blue, Cyan and Green directions, respectively.

In addition, an ink key indicator 1409/1509 extends across the top ofthe page and includes one space for each ink key. In this case there are32 keys and as such 32 spaces. In the illustrated example, ink keyregions 9-16 have been selected for adjustment. These ink keys areindicated as being selected in the ink key indicator 1403. Additionally,a small image of the printed product 1408/1508 is positioned on the userinterface and also indicates which region is being adjusted.

In another construction, shown in FIG. 8, the color adjustment screen805 is displayed on the video display 403. The screen includes an a*b*plane graph 801 showing a portion of the a*b* plane, and an L* numberline 802 showing a portion of the range of L* values. There is an a*b*mark 803 on the a*b* plane graph 801 to indicate the average a*b* valuefor the selected area, and an L* mark 804 on the L* number line 802 toindicate the average L* value of the selected pixels.

Color adjustments are made by selecting either the a*b* mark 803 or theL* mark 804 using the input device in the color adjustment screen 805.The mark (803 or 804) is then repositioned by moving the input device asdesired.

The resultant output of both color adjustment screens 805 and 1400 is aset of changes in L*, a*, and b* values 408.

For simplicity, the color adjustment screen 805 is depicted on the videodisplay 404 which is used to display images such as scanned images 302,a target image 303, and/or a predicted image 402. In one implementation,the user may toggle the video display 404 between the display of imagesand the display of the color adjustment screen 805. For example, FIGS.14 and 15 include side tabs 1410/1510 that allow for toggling betweenthe two user interfaces 1400, 1500.

In another embodiment, there are two separate video displays 404 inproximity, with one video display 404 being used to display images andthe other to display control screens such as the color adjustmentscreens 805, 1400, 1500. In this embodiment, the colorimetricrequirements for the video display 404 used to display control screensare considerably less stringent than for the video display 404 used todisplay images.

In the preferred embodiment, images and control screens are presentedsimultaneously on the same video display 404. In addition, the displayprovides the user the ability to display a reference image, such as thetarget image 303, next to the scanned image 302 in a split screen formatand allows for pan and zoom. In a preferred construction, a pan or zoomin one of the split screens produces an equal pan or zoom in the otherof the split screens such that the two images always correspond to oneanother.

As the set of changes in L*, a*, and b* values 408 are adjusted throughthe color adjustment screens 805 and 1400 a tentative target image 403is created. The tentative target image 403 may be created, for example,as follows. First, the entire target image 303 is copied to thetentative target image 403. Then, the color value of each pixel in thetentative target image 403 is adjusted by adding the changes in L*, a*,and b* values. Alternatively, the changes may be construed as beingmultiplicative rather than additive in nature.

As illustrated in FIG. 4b , when the tentative target image 403 isassembled, it will be passed to a second color image control system 300b. This system functions the same as the color image control system 300,except that it works to find the set of tentative SID changes 407 thatwill allow the scanned image 302 to appear most like the tentativetarget image 403, rather than the target image 303. Note that a singlecolor image control module 300 may perform both functions; there is noneed for two separate modules.

The output of the color image control system 300 b is a set of tentativeSID changes 407. From here the functioning is along the lines of that inthe embodiment shown in FIG. 12. As a result, a predicted image 402 isdisplayed on the video display 404 which predicts what the entire imagewould look like if the adjustable ink control devices were adjusted soas to bring the selected area to be 702 as close as possible to therequested color change.

As the user makes color adjustments to the selected area 702 through thecolor adjustment screens 805, 1400, 1500, the predicted image 402 willpreferably be updated on the video display 402. In this way, feedbackwill occur much faster than the traditional mode where the pressoperator must wait for the color change to settle out and then retrievea press sheet 101. Thus, the control of color is faster and moreaccurate. Also, since the feedback is much faster, a press operator canbe trained much quicker, and the press set-up can be approved morequickly and remotely if desired.

When the user is satisfied with the appearance of the predicted image402, the update or OK button 806 on one of the color adjustment screens805, 1400, or 1500 is selected. This will cause the user interface 401to update the target image 303 so that the image color control system300 will control to the adjusted color values as is discussed below.Various alternatives are possible for how to update the target image303. The tentative target image 403 may be used as the new target image303. Alternately, the predicted image 402 may be used for that purpose.In the preferred embodiment, the tentative ink key openings 407 may beloaded directly into the ink key openings 207. After a suitable delay,the target image will then be updated with the scanned image 302.

A cancel button 807 is also available for the user to abandon anytentative adjustments.

It may be useful for the target color values of the selected area 702 tobe included on the color adjustment screen 805. This is depicted as thehollow marks 808 and 809. It may also be useful for the color values tobe displayed numerically instead of, or in addition to the graphicaldisplay.

In the preferred embodiment, the image scanner 301 is positioned tomeasure printed product 206 as it moves through the press. The imagescanner 301 measures the spectra at each of 128 points along a scan line1003 perpendicular to the direction of web movement while the web is inthe print device. These points are at a resolution of 0.010 inches sothat the field of view is 1.28 inches. As the printed media 206 advancesby 0.010 inches, another set of spectra are collected, and another, andso on to cover a full repeat at a resolution of 100 DPI. Of course otherresolutions or point quantities could be employed if desired. Inaddition, a scanner capable of measuring more than 128 points, ormultiple scanners could be employed if desired.

The image scanner 301 is mounted on a transport that moves laterally(i.e. perpendicular to the web movement direction) at a rate of oneone-hundredth of the web speed. Thus, for a print job with a repeatlength of 60 inches, the image scanner 301 will move laterally 0.60inches from one repeat to the next. A portion of the image scanner swath1001 is illustrated in FIG. 10 over three repeats. Again, other ratesand print job sizes also function with the present invention.

The image scanner swath 1001 will typically pass over and collectmeasurements from corresponding image portions (e.g. 1002 a, 1002 b, and1002 c) on five or six consecutive repeats. By performing crosscorrelation between the most recently acquired data and data acquiredfrom previous repeats, it is possible to determine the alignment of oneset of data with the first for each repeat, and thereby average thecorresponding image portions. This averaging is beneficial in that itreduces normal process fluctuations as well as sampling noise from theimage scanner 301.

FIG. 11 schematically illustrates a portion of the preferred embodimentof the image scanner 301. The image scanner 301 includes an imagingspectrograph 1101 and a two-dimensional imaging device 1102. The imagingspectrograph 1101 is constructed so as to project an image of the scanline 1003 onto a two-dimensional imaging device 1102. In oneconstruction a CCD or a multi-tap CCD with a horizontal resolution of128 pixels and a vertical resolution of 32 pixels is employed. In thisconstruction, the projected image of the scan line is deployed spatiallyin the horizontal direction and spectrally in the vertical direction. Itis to be understood that alternate light sensing technologies (e.g.CMOS) may be applicable.

In FIG. 11, light leaving a point 1103 along the scan line 1003 isfocused by the imaging spectrograph 1101 onto a vertical line 1104 onthe two-dimensional imaging device 1102. The point of focus on thisvertical line 1104 is dependent upon the wavelength of the light. Higherwavelength light, for example, light at 700 nm, will be focused at point1105 near the uppermost line of the two-dimensional imaging device 1102.Lower wavelength light, for example light at 390 nm, will be focused ata point 1106 near the lowermost line of the two-dimensional imagingdevice 1102. Thus, the amount of light impinging the two-dimensionalimaging device 1102 along the vertical line 1104 will be indicative ofthe spectrum of light emitted from the point 1103.

In a similar fashion, light leaving a second point 1107 along the scanline 1003 will be focused along a vertical line 1108 on thetwo-dimensional imaging device 1102 so that the light impinging thetwo-dimensional imaging device 1102 along the vertical line 1108 will beindicative of the spectrum of light emitted from the point 1107.

Thus, the row address of the two-dimensional imaging device 1102indicates the wavelength of the measured light, with the bottom-most rowcollecting light at for example 390 nm, the next row up collecting lightat for example 400 nm, and so on, up to the 32nd row, which collectslight at, for example, 700 nm. The columns of the two-dimensionalimaging device 1102 correspond to positions along the scan line 1003.Thus, following the above example, the image scanner separates 128spatial points of light, each 0.010 inches in length for a total lengthof 1.28 inches, into up to 32 different wavelengths or colors. Ofcourse, a finer or coarser gradation of the wavelengths could beemployed if desired. As such, the points could be divided into more orfewer than 32 wavelengths.

In the preferred embodiment, the imaging spectrograph 1102 is anImSpector V8E with 30 um slit size as manufactured by Specim of Oulu,Finland, equipped with a Xenoplan 4:1 bilateral telecentric lens fromSchneider Optics of Hauppauge, N.Y. With this lens, the pixel sites onthe two-dimensional imaging device 1103 will be 63.5 μm wide by 150 μmtall.

Web speeds for a typical web offset press place constraints on thetwo-dimensional imaging device 1103. Web offset presses typicallyoperate at speeds up to 3500 FPM, which is equivalent to 700 IPS. Tocollect 100 DPI images, the frame rate for the two-dimensional imagingdevice 1103 must be at least 70,000 frames per second. To read thetwo-dimensional imaging device 1103 at this rate, it is beneficial tohave one tap per wavelength channel, so that there are a total of 32lines of output (i.e., 32 taps).

It will be recognized that certain applications may require more or lesswavelength channels, that the range of wavelengths may extend beyond 390nm to 700 nm, and/or that the required frame rates may be slower orfaster. For example, 64, 128, or more channels may be employed toprovide additional color depth if desired.

The spectral data output from the two-dimensional imaging device 1103will be processed in a conventional manner to obtain CIELAB, sRGB, orother color-correct images. Such processing may include, for example,corrections for nonlinearity, subtraction of photometric zero values,normalization against a white reference, and calculation of XYZ values.Corrections for scattered light may also be required.

It is to be understood that variations on the embodiment of the imagescanner 301 are within the scope of this invention. The pixel size of0.010 inch by 0.010 inch for the image scanner 301 is given by way ofexample and will depend upon the application. There may be more than orless than 128 measurements made along a scan line 1003. The imagescanner 301 may scan some number of repeats without moving and then betransported laterally to scan a separate swath. In some applications, itmay be preferable that the image scanner 301 span the full width of theprinted media 206, or that multiple image scanners 301 be mounted acrossthe printed product 206 so that lateral transport is not required.

In one embodiment, the image scanner 301 can be a standard flatbedscanner, equipped with ICC profiling software so as to convert RGBmeasurements into CIELAB values. The step of ICC profiling software isdisadvantageous in that a separate profile may be needed for eachcombination of ink type and printed media. This need may be obviatedthrough the use of a scanning spectrophotometer, such as the DTP70 fromXRite of Grand Rapids, Mich., which measures the spectral reflectance ata numerous locations over a sheet. In these embodiments, measurementsare not made directly on the print device 205 so that manualintervention is required to make the measurement.

In an alternate embodiment, the image scanner 301 is mounted so as toview a portion, say for example, one page, of the printed media 206directly. A xenon strobe, tungsten-halogen bulb, white LEDs, or otherillumination sources may be used to illuminate the printed product 206.The image scanner 301 includes a color separation prism which spectrallyseparates the incoming light and projects the light onto three areasensors, such as CCDs (charge-coupled devices). The color separationprism preferably includes interference filters so designed as to providespectral responses of the three area sensors that can be translateddirectly into XYZ tristimulus responses as defined in CIE 15.2.

The illumination will preferably impinge the printed media at 45 degreesand the image scanner will be so designed as to view light reflectednormal to the printed media 206 in accordance with the 45 degree/normalilluminating and viewing conditions specified in CIE 15.2. Otherconfigurations of illumination and detection of light may be used, ofcourse, as appropriate.

FIG. 5 shows still another alternate embodiment of the image scanner301. FIG. 5 illustrates the image scanner 301 as including anillumination assembly 506 and a camera assembly 507. The illuminationassembly 506 is nominally comprised of a light source 501 (shown in FIG.6), and an illumination lens 502. The light source 501 is preferably arow of white LEDs 601, such as the Luxeon K2 manufactured by Lumileds,or equivalent.

The light emitted from the light source is collimated by virtue of anillumination lens 502. This lens may be a cylindrical Fresnel lens suchas available through Edmund Optics. Alternately, the illumination lens502 may be a parabolic or elliptical reflector. In another embodiment,the illumination lens 502 may be of the catadioptric variety, combiningboth refractive and reflective elements, such as are available throughFraen SRL of Italy.

In this embodiment, the illumination lens 502 is positioned so as tocollimate the light. The entire illumination assembly is oriented so asto provide a sheet of illumination that impinges the printed web 206 at45°±5°. Two illumination assemblies 506 may be included, one upstreamand one downstream from the camera assembly 507. These two illuminationassemblies 506 are oriented so as to illuminate substantially the sameregion of the printed web 206.

A portion of the light reflecting from the web is detected by the cameraassembly 507. This camera assembly 507 is nominally comprised of aspectral filter 503, an imaging lens 504, and an imaging sensor 505.

The reflected light is passed first through a spectral filter 503. Byvirtue of the spectral filter 503, the total spectral response of theimage scanner 301 approximates the tristimulus spectral responses whichare used to measure CIELAB color values.

An imaging lens 504 is used to focus an image of the printed product 206onto the imaging sensor 505. This imaging sensor 505 is preferably alinescan CCD sensor, although it could be any other suitablelight-sensitive devices, such as an array of photodiodes. In order toacquire an image of the web, the sensor is provided with a signalindicative of the motion of the printed product 206, such as an encodersignal, to alert the imaging sensor 505 to acquire the next line.

The imaging lens 504 and imaging sensor 505 may, for example, beselected so as to achieve for example a resolution of 100 DPI. If theimaging sensor 505 is a linear sensor with 128 pixels, the width of thefield of view would then be 1.28″. In order to scan the printed web 206,the image scanner would collect a 1.28″ strip of an entire impression,then move laterally to position for the next 1.28″ strip. This processwould continue until an image of an entire impression has been created.

In general, the measurement of CIELAB values will require at least threechannels of information, collected through three separate filters. Thiscan be accomplished in a variety of ways. In one embodiment, a set ofthree spectral filters 503 are mounted on a rotating turret. One at atime, the spectral filters 503 are interposed between the printed web206 and the imaging sensor 505. Thusly, the multiplicity of channels arecollected, each of a different impression. The accuracy of the spectralresponse can be tailored to the tristimulus curves with the addition ofmore than three such spectral filters 503. There may be, for example,fifteen to thirty different spectral filters 503, each spectral filterbeing a narrow bandpass filter.

In another embodiment, the imaging sensor 505 is a trilinear linescanCCD. Such a sensor is comprised of three parallel lines of sensingelements in close proximity. Each of the sensors is equipped with aspectral filter 503. In this way, three channels of information arecollected simultaneously in the field of view.

In yet another variation on this embodiment, a color separation prism isused to separate the incoming light spectrally to three separate imagingsensors 505. Such color separation prisms are commonly found inso-called three chip color cameras. See, for example, U.S. Pat. No.4,268,119.

The positioning of the spectral filter 503 need not be between theprinted web 206 and the imaging lens 504. In general, the spectralfilter 503 may be interposed anywhere between the illumination source501 and the imaging sensor 505.

In yet another embodiment of the image scanner 301, the illuminationsource is a set of red, green and blue LEDs. The printed web 206 isalternately illuminated by the red LEDs, the green LEDs and the blueLEDs. In this way, the spectral filter 503 is in effect combined withthe illumination source.

FIGS. 19 and 20 illustrate an alternative image capturing system thatcould be employed in the virtual ink desk 400. Many of the modules andlogical structures described are capable of being implemented insoftware executed by a microprocessor or a similar device or of beingimplemented in hardware using a variety of components including, forexample, application specific integrated circuits (“ASICs”). Terms like“controller” and “processor” may include or refer to both hardwareand/or software. Furthermore, throughout the specification capitalizedterms are used. Such terms are used to conform to common practices andto help correlate the description with the coding examples and drawings.However, no specific meaning is implied or should be inferred simply dueto the use of capitalization. Thus, the claims should not be limited tothe specific examples or terminology or to any specific hardware orsoftware implementation or combination of software or hardware.

Embodiments of the invention include a color measurement deviceconfigured to detect color printed on a moving web. In one specificembodiment, the invention provides a color measurement device thatincludes a light source, a light dispersal element, a sensor array, anda processor.

FIG. 19 shows a side schematic view of a portion of a printing press5100 configured to print an image on a substrate 5104 traveling from anupstream position 5108 to a downstream position 5112 in a directionindicated with arrow 5116. In some embodiments, the substrate 5104 is amoving web. A printing mechanism 5120 prints an image on the substrate5104 as the substrate 5104 is moving in the direction 5116. The printingpress 5100 also includes a color measurement device 5124 that ispositioned downstream from the printing mechanism 5120, and above thesubstrate 5104. The color measurement device 5124 generally measurescolor values of the image printed on the substrate 5104. In this way,the printing press 5100 can adjust its printing process if necessary.

In the embodiment shown, the color measurement device 5124 includes alight emitting source 5128 positioned at an angle relatively to thesubstrate 5104 to illuminate the substrate 5104. In some embodiments,the angle is about 45°. The light source 5128 is generally a spectrallyknown calibrated light source. For example, the light source 5128 isactivated to illuminate light onto a white tile for calibration. Aportion of the light is reflected and used as default light sourcevalues. Other calibration techniques can also be used to calibrate thelight source 5128.

In some embodiments, the light source 5128 includes one or morelight-emitting-diodes (“LED's”) 5132 to emit or generate light, a beamhomogenizer or a homogenization lens 5136 to homogenize or to smooth outany irregularities of the emitted light, and a collimating lens 5140 tocollimate or parallelize the light before illuminating the substrate5104. Although the light source 5128 is shown to include an LED, thelight source 5128 in other embodiments may have other types of lightemitting devices such as but not limited to strobe lights, conventionalincandescent bulbs, a halogen bulb, and fluorescent bulbs. Although, asshown in FIG. 20, light emitted from the LED's 5132 is a collimatinglens 5140, the light source 5128 can also include a parabolic mirror(not shown) having the LED's 5132 at one of its foci. In this way, lightemitted from the LED's 5132 is also collimated. In some embodiments, thelight source 5128 is activated at a predetermined frequency. In otherembodiments, the light source 5128 can be continuously activated forcontinuous scanning or monitoring purposes.

After the printing mechanism 5120 has printed on the substrate 5104, thesubstrate 5104 continues to travel in the direction 5116. As thesubstrate 5104 arrives below the color measurement device 5124, acontroller 5142 activates the light source 5128 to emit light. Althoughthe controller 5142 is shown as external to the color measurementdevice, the controller 5142 can also be implemented as an internalcomponent of the color measurement device. The light travels through thehomogenizing lens 5136 and the collimating lens 5140 to be homogenizedand collimated. At least a portion of the light, after being homogenizedand collimated, reaches and illuminates the substrate 5104 at adirection indicated by arrow 5144.

Generally, when the emitted light reaches the substrate 5104, theemitted light illuminates one or more line units or pixels that define aline or pixel thickness and a line length. For example, a line unit canhave a size of 1 unit or pixel thick and 128 units long for a resolutionof 75-200 dots-per-inch. The substrate 5104 subsequently reflects aportion of the emitted light in a direction indicated by arrow 5148among other reflected directions such as direction indicated by arrow5150. The direction indicated by arrow 5148 is generally perpendicularto the substrate 5104.

A camera assembly 5152 positioned above the substrate 5104 then receivesa portion of the reflected light for further processing. For example,the camera assembly 5152 captures the reflected light and processes itto determine if images printed on the substrate 5104 meet certainprinting requirements. If the controller 5142 considers the print imagesas unacceptable, the controller 5142 will signal different components ofthe printing press 5100 to make corresponding adjustments. For example,if the controller 5142 determines that images printed on the substrate5104 project insufficient color intensity, the controller 5142 signalsthe printing mechanism 5120 to release its blades to allow more ink flowfrom corresponding ink reservoirs. In other instances, if the controller5142 determines that images printed on the substrate 5104 are improperlyaligned with respect to edges of the substrate 5104, the controller 5142signals mechanism controlling movements of the substrate 5104 to realignthe substrate 5104 accordingly.

In the embodiment shown, the camera assembly 5152 includes a telecentriclens system 5156 to focus the reflected light. The telecentric lenssystem 5156 can be an objective lens that focuses on images printed onthe substrate 5104. In some embodiments, the telecentric lens system5156 automatically adjusts its focus due to varying distances betweenthe substrate 5104 and the color measurement device 5124 as thesubstrate 5104 travels. Furthermore, in some embodiments, thetelecentric lens system 5156 includes a plurality of positive lensessuch that the telecentric lens system 5156 can adjust its focus on theimages. In other embodiments, the telecentric lens system 5156 includesonly one positive lens.

The camera assembly 5152 also includes a light dispersal system 5160 toreceive the focused light arrived from the telecentric lens system 5156through an aperture or an entrance slit 5164. Exemplary light dispersalsystems or dispersal elements 5160 include one or more of a prism, adiffusion lens, and a diffraction grating to spectrally break thefocused light. In one particular embodiment, the light dispersal system5160 includes an ImSpector Spectrograph from SPECIM, which breaks lightinto a continuous spectrum.

In the embodiment shown, the light dispersal system 5160 spectrallybreaks the focused light received through the slit 5164 into acontinuous spectrum. Although the light dispersal system 5160 as showngenerally breaks the light across a visible light spectrum, the lightdispersal system 5160 can also be configured to break the light into aspecific predetermined spectrum. In the embodiment shown, the lightdispersal system 5160 simultaneously breaks the focused light into acontinuous spectrum that is then collected or sensed in 32 spectralbands. In this way, the light dispersal system 5160 makes all light orcolor spectra available essentially simultaneously at a plurality ofoutputs.

Once the light dispersal system 5160 has spectrally broken the focusedlight into a plurality of color spectra, the light dispersal system 5160projects the spectra onto a sensor array circuitry 5168, detailedhereinafter. In some embodiments, the sensor array 5168 is asemiconductor chip positioned adjacent to the light dispersal system5160 to receive the spectra. In other embodiments, the light dispersalsystem 5160 has output pins or output cables (e.g., a fiber optic cable)to connect to the sensor array circuitry 5168. In the embodiment shown,the sensor array circuitry 5168 includes a plurality of sensingelements. Each of the sensing elements corresponds to each of theavailable spectra. The sensor array circuitry 5168, through each of thesensing elements, essentially simultaneously generates a density valuefor each of the spectra available. The controller 5142 subsequentlydetermines the colorimetric values of the images on the substrate 5104.In other embodiments, a dedicated processor is embedded within thesensor array circuitry 5168 such that colorimetric values can beefficiently determined, as detailed hereinafter.

FIG. 20 shows an exemplary sensor array circuitry 5168 in the form of amicrochip or a chip. As shown, the sensor array circuitry 5168 includesa plurality of complementary metal oxide semiconductor (“CMOS”) digitalimage sensors for sensing the spectrally broken light transmitted fromthe light dispersal system 5160. In some cases, the sensors have avideo-graphic array (“VGA”) quality image resolution of about 640H×480V.As shown, the sensor array circuitry 5168 chip has 32 parallel arrays orchannels 5204, and each of the 32 channels has a 128 pixel linear sensorarray 5208. The 32 sensor channels have a common clock 5212 and linestart inputs 5216. Each of the sensing elements is also coupled to acorresponding buffer 5220 and output line 5224. In some embodiments, thesensor array circuitry 5168 can also include a processor 5228 forprocessing the sensed signals and determining colorimetric values of theimages on the substrate 5104.

In some embodiments, the sensor array circuitry 5168 chip also hasmultiple input pins. In one particular embodiment, the sensor arraycircuitry 5168 has an active area dimension of 6.4 mm (or 128 pixels) by4.8 mm (32 columns/channels). In such a case, the sensor array circuitry5168 has a pixel size of about 50 μm spacing (6.4 mm/128 pixels), and acolumn pixel size of about 150 μm spacing (4.8 mm/32 column). The sensorarray circuitry 5168 also has a maximum line rate of about (660inch/second×100 line/inch), or 66,000 lines per second, and a maximumdata rate of about (66,000 lines/second×128 pixels), or 8.5 Megapixels/second. Similarly, the sensor array circuitry 5168 has a minimumsaturation output voltage of about 1.5 V full scale, a maximum outputnoise voltage of 1 mV RMS, a maximum output voltage nonlinearity ofabout 0.4% full scale, a maximum pixel response nonuniformity of about7%, a maximum dark signal nonuniformity of about 5%, a peak responsivityof about 20 V/(μj/cm²), and a minimum saturation exposure of about 75nj/cm².

The image scanner 301 is not constrained by the embodiments describedherein. For example, the image scanner 301 or portions thereof mayincorporate aspects of the image sensors described in U.S. Pat. No.5,724,259, or of various components described in the co-pending patentapplications US 2004/0177783, US 2005/0099795, and US 2005/0226466. Saidpatent and said patent applications are herein fully incorporated byreference.

It is possible that the prepress data may be available at a certainresolution, say 100 DPI, and the image scanner 301 may scan the printedproduct 206 at another somewhat lower resolution, say 25 DPI. In thiscase, the color image control system 300 could be successfully utilized,as resolutions as low as 10 DPI have been tested and found to give goodcolor control results. However, resolutions lower than 72 DPI may beobjectionable for viewing by users, as text would generally not belegible.

To resolve this issue and allow for situations where the image scanner302 has resolution of less than 72 DPI, we employ a process calleddisadumbration. Adumbrate means to give a sketchy outline of. In thiscase, a reduced resolution scanned image 302 is an adumbration of thefull resolution scanned image. Disadumbration is the process ofrestoring resolution, as much as is possible.

In one embodiment of disadumbration shown in FIG. 18, the resolution ofthe target image 303 is reduced to the same resolution as the scannedimage 302, so as to produce the reduced resolution target image 1801.

The reduced resolution target image 1801 is then combined with thescanned image 302 to yield a reduced resolution difference image 1802.This image can be super-sampled and blurred to the resolution of thetarget image 303 to give the full resolution difference image 1803. Thisfull resolution difference image 1803 can then be combined with thetarget image 303 to yield a good quality, representation of the scannedimage 302 at an optimal resolution.

Thus, the target image 303, which is at full resolution, will providesharp detail to the image, and the reduced resolution difference image1802 will provide the color changes.

Supersampling can be done by simple pixel replication, by aninterpolated scheme. Alternately a more sophisticated process may beused that takes the CMYK separation information into account. If, forexample, a reduced resolution pixel is calling for an area to be darker,this color change should be apportioned to full resolution pixels wherethere is coverage that could produce a darker image, and not tonon-inked pixels.

Other implementations of disadumbration are possible within the scope ofthis invention. For example, disadumbration could be performed throughthe use of deconvolution, or Weiner deconvolution, or Van Cittertdeconvolution.

This disadumbration process can be used as described here for display ofa scanned image 302. The same technique can be used to display thepredicted image 402 at full resolution when only a reduced resolutionscanned image 302 is available.

Within the colorbar control system 200, the colorbar measurement system208 ascertains the color characteristics of various control patcheswithin colorbar 203 portion of the scanned image 302. The colorcharacteristics may be measured on solid single ink patches to yield SID(solid ink density) values. These color characteristics may for exampleinclude densitometric measurements or colorimetric measurements.

These colorbar measurements are passed to a SID control system 209,which calculates the adjustments for the adjustable ink control devicesso that the control patches will be within a tolerance of a set oftarget SID values 1201. Such colorbar control systems 200 are well knownin the art, as seen in for example, U.S. Pat. No. 5,724,259 and U.S.Pat. No. 6,142,078, which are fully incorporated herein by reference.

The color image control system 300 receives the scanned image 302 andaligns this image with a target image 303 within the color imageprocessing module 1203 so that pixels corresponding to the same imagecontent may be compared. A subtraction is performed between thecorresponding pixels. This difference (i.e., the color error) is thenused to create an effective colorbar measurement 1202 to be used by thecolorbar control system 200 in place of the actual colorbarmeasurements.

In order to compute the effective colorbar measurement 1202, the colorimage processing module 1203 performs linear regression so as to find aset of SID changes that would minimize the color error. A sensitivitymatrix 305 is used to estimate the amount of color change that wouldoccur at every pixel in the scanned image 302, if a given change in SIDvalues were to take place as a result of changes in the adjustable inkcontrol devices.

Such color image control systems 300 are well known in the art. See forexample U.S. Pat. No. 5,967,050, which is fully incorporated herein byreference.

Alternately, the color characteristics may be measured on controlpatches other than solid single ink patches, for example, three colorgray patches. The results are then translated into effective SID values,and passed to the SID control system 209. Such so-called gray balancecontrol systems are well-known in the art, for example U.S. Pat. No.4,852,485, which is herein incorporated by reference.

In the embodiments so far described, the color image control system 300operates to generate target SID values 1201 for a colorbar controlsystem 200. There are several advantages to this approach. One advantageis that the color image control system 300 is dependent on theidiosyncrasies of the particular print device 205. Some presses, forexample may deploy a greater or lesser amount of ink than another for agiven ink key position. In addition, the effect of a certain opening isdependent upon the coverage for that ink key zone, so the values in thesensitivity matrix 305 will depend upon more than just the CMYK valuesfor that particular pixel.

Another advantage is that this arrangement retrofits well with existingcolorbar control systems 200.

In addition to reducing complication of the color image control system300, the sensitivity matrix can now be expressed in more universalunits, as derivatives of L*, a*, and b* values with respect to densitiesof cyan, magenta, yellow and black inks.

The advantages nonetheless, it is possible for the virtual ink desk 400to be operational with a color image control system 300 which is notused in conjunction with a colorbar control system 200 as illustrated inFIGS. 4 and 9. In this case, the color image control system dealsdirectly in the currency of the print device (e.g. ink key moves)without the intermediate artifice of SID values.

In a practical application of the predictive feature, it is necessary tolimit the changes in density (Δ_(C), Δ_(M), Δ_(Y), and Δ_(K)) to valueswherein the actual density is physically attainable. Such a range forblack ink, for example, might be between densities of 0.8 D to 2.0 D.

The relationship between density and L*a*b* values represented in thesensitivity matrix 305 is a linear approximation which is valid over acertain range of density. In applications where a greater density rangeis required, or where greater accuracy is required, multiple sensitivitymatrices may be required for different density ranges. Alternately,second order terms may be included.

In yet another embodiment, the entries in the sensitivity matrix 305 arecalculated based on the density, rather than being fixed values. In thisembodiment, it may be beneficial to compute large changes as a series ofsmaller changes, recalculating the sensitivity matrix 305 after eachsmall change.

As discussed, the virtual ink desk 400 includes a prediction module 405that uses the color adjustments made by the user to determine anadjustment to the print device 205 (i.e., an adjustment to the inkcontrol devices or the ink keys). The adjustment will generally have thedesired effect in the area of concern; however it may cause otherunexpected changes in adjacent areas. Thus, the prediction modulegenerates a predicted image 402 indicative of the printed image 206 fromthe print device 205 following the implementation of the adjustment.This predicted image 402 can than be reviewed and compared with adesired image to verify that the adjustment produces the desired output.

In a variation of the embodiment illustrated in FIG. 12, when the userselects an ink key zone 103 immediately adjacent ink key zones 103 arealso selected, and perhaps the ink key zones immediately adjacent tothem. In this way, a multiplicity of adjacent ink key zones 103 will beselected. When an adjustment is made, the full adjustment will be madeto the middle of the multiplicity of ink key zones 103. A smalleradjustment will be made to the directly adjacent ink key zones 103, anda still smaller adjustment will be made to the furthest ink key zones103. This adjustment scheme will mimic the adjustments that pressoperators normally make.

In another embodiment, the user selects pixels within an image asbefore. Rather than adjusting (directly or indirectly) the target valuesfor these pixels, the user adjusts the tolerance for that collection ofpixels. This is accomplished by modifying the weighting for thatcollection of pixels in the linear regression. This may be appropriate,for example, when the target image 303 has the proper color values, butother constraints in the image drive these pixels on the printed web 206to have unacceptable color values. Increasing the weighting for specificpixels will force color differences of those pixels to be given extraconsideration in balancing the color differences within an ink key zone103.

These embodiments of the color adjustment screens 805, 1400, 1500 aremeant as examples of how the user may be presented with a screen toeffect a color change. Adjustments may be made in colorimetric values orin CMYK density values as illustrated or they may be adjusted in anyother suitable color space, such as RGB or HSI. The target pixels toadjust may be within a small contiguous region, may include severaldisjoint regions throughout the printed sheet, or they may encompass anentire ink key zone 103, an entire page, or the entire printed web 206.

It will be appreciated that an intuitive alignment between an image ofthe saleable work 204 and the rocker switches 102 as illustrated in FIG.1 is no longer necessary in this invention. The computer is responsiblefor determining which ink keys correspond to any given portion of theimage. It is no longer necessary for the user to use the rocker switches102. Since it is no longer necessary for the user to unfold the printedsheet 101, the virtual ink desk 400 will no longer require a flatsurface that is the size of an entire impression. Thus, the virtual inkdesk is considerably more compact than the traditional ink desk 100.

It is still beneficial to maintain intuitive alignment between thescanned image 302 and the target image 303. This is accomplished whenthe images are shown in a split screen mode, whereby the images will panand zoom together.

Note that since the images to be compared are both video display images,i.e. emissive images rather than a mixture of emissive and reflective,the lighting requirements are far less critical.

FIG. 16 shows a user interface screen 1600 in which a split screen isemployed. FIG. 16a shows an alternate view of the same user interfacescreen 1600. The left pane of the screen 1601 shows the target image 303or the scanned image 302, while the right pane shows an enhanceddifference 1602 between the proof and the scanned image 302, sometimesreferred to as a blobular image. This function is important to pressoperators and to prepress technicians because it gives them informationnot previously available—global color shifts in image areas as well as amap of inline conflicts.

The blobular image tool gives the operators spatial information aboutthe color errors so they can understand the location and nature of theproblem to take corrective actions. One way of providing context for theerrors is to show the scanned image 302 and the error data side by side,as shown in FIG. 16. Another option would be to blend the error imagewith a ghosted, grayscale version of the target image 303 or scannedimage 302. This blending gives more precise information about thelocation of areas with a significant color difference. FIG. 16 alsoemploys this technique.

In the blobular image, a neutral gray represents no color difference.Any difference from the neutral gray represents an area where the targetimage 303 does not match the scanned image 302. A colored arearepresents an error in hue and an area of saturation different from theneutral represents a lightness error.

In the case of an inline conflict, the user can observe that, in a givenvertical strip of the image, one area 1603 may have an error in a givendirection, for example in the positive a* direction, whereas anotherarea in the same strip 1604 may have an error in the negative a*direction. Depending on the content of the printed materials, theseserrors may balance and not result in an ink key move. Thus, withoutoperator input, the errors are not automatically correctable.

To resolve the inline conflict, or other color shift effects, the pressoperator may choose an important area of the image to emphasize overanother. The weightings then result in a different predicted image 402or a different blobular image representing a new set of compromises,which may be more desirable to the print buyer.

In many cases, after the control system has minimized the color errors,the color differences are relatively small, so they must be amplifiedand enhanced to give useful information to the user. To accomplish this,a digital curve or lookup table is constructed to emphasize delta rangeswhile diminishing the importance of others. Either the scanned image 302or the blobular image should generally be digitally filtered to removethe noise inherent in the printing processes, imaging processes, as wellas the alignment and the fine-grained comparison. Operators of thevirtual ink desk may also adjust the degree of amplification to helpdistinguish color differences which require decisions or adjustmentsverses those which can be considered to be within an acceptable range.

Regions of interest for setting weightings, making color corrections, orreporting may be created from within the virtual ink desk and may alsocome from a variety of external sources, such as is illustrated in FIG.17. Print buyers and press operators may require real-time and postproduction reporting of the color conformance of certain areas inprinted image. The virtual ink desk may import these regions fromauxiliary software tools external to the virtual ink desk, such as a website, as well as from commercially available tools, such as ADOBEPHOTOSHOP. A number of standard image file formats exists, notably TIFF(Tagged Image File Format) and EPS (Encapsulated Postscript) provide forthe specification of regions of interest. The print buyer may providefiles in these or other similar formats. These files and their enclosedregions may then be imported into the virtual ink desk and used asregions of interest.

While the term “ink key” applies strictly to an arrangement whereby ascrew mechanism actuates the flexure of a blade in order to meter ink,it will be understood that the invention herein applies equally well tocontrol of any ink metering devices, such as the ratchet for the inkball and segmented ink keys, as well as other ink metering technologiessuch as ink jet or ultrasonic ink metering.

This invention may be found to be beneficial for the control of any ofthe operating parameters of the press beyond the adjustment of ink flow.The invention may by advantageously applied to the control of dampeningsolution, for example. Additionally, color-to-color register may becontrolled via the invention, especially with wider webs where fan-outand plate cocking are more critical.

It will be understood that, while this disclosure has been described interms of web offset presses, the invention may be advantageously appliedto other types of printing presses, such as sheet fed presses,flexographic presses or gravure presses.

The abbreviation “CMYK” has been used throughout to generically indicatethe set of inks that are used on any particular printing job. Typically,these inks are cyan, magenta, yellow and black inks. Depending upon theprinting job, some of these inks may be omitted, and other specialtyinks may be added. It is to be understood that this invention is notlimited to this particular set of printing inks.

The invention has herein been described as operating in conjunction witha color image control system 300. It will be understood that it couldalternately operate in conjunction with a colorbar control system 200.This invention also could be used without a color control system,whereby the press operator is effectively the color control system.

In operation, an approved proof is used to make an initial ink key orink adjustment mechanism setting. The print device is operated toproduce printed product based on these initial ink key settings. Theimage capturing device captures a color-correct image of the printedproduct which is transmitted to the virtual ink desk. The virtual inkdesk may be located locally (i.e., in the same building or printingfacility as the print device) and/or may be located remotely (i.e., in adifferent facility or city). The captured image is compared to theoriginal proof to determine if the colors match. The virtual ink deskallows for a side-by-side comparison of the proof or target image andthe captured image. In addition, the images can be zoomed or panned toallow for a thorough inspection. If any color changes are desired, theuser (e.g., press operator and/or remote print buyer, etc.) selects thedesired pixels, area, or ink key zones for adjustment. The user thanaccesses one or more of the variety of user interface screens 1400, 1500to make the color adjustment. As the color is adjusted or after all ofthe color adjustments are made, the predictive module calculates theactual ink key adjustments required to achieve the desired colorchanges. In addition, a predictive image of the printed product isgenerated. The predictive image is indicative of the printed productfollowing implementation of the calculated ink key moves. If thepredictive image is not satisfactory, additional adjustments can bemade. Once the image meets the requirements of the user, the ink keysettings are transmitted to the print device and printing continues. Thepredictive image can then be substituted for the target image to allowthe color control system 300 to make minor ink key adjustments duringprinting to assure that the printed product matches the predicted image.Alternatively, another image of the printed product is captured afterthe ink key adjustments have become fully effective and this image isused as the target image.

Thus, the invention provides, among other things, a new and usefulvirtual ink desk for use with a print device. The virtual ink deskincludes a prediction module that predicts the results of a projectedadjustment to the print device to stream line the proofing process atthe print device.

What is claimed is:
 1. A method comprising: receiving, from an imagecapturing device, a captured image of a printed product on a printingpress; transmitting the captured image to a display located remote fromthe image capturing device; receiving input data from a remote inputdevice; determining an adjustment to a setting of at least one of aplurality of ink control devices of the printing press based on theinput data; and transmit a control signal to adjust at least one of aplurality of ink control devices of the printing press based on thedetermined adjustment.
 2. The method of claim 1, wherein the input datarepresents a modification to the displayed captured image received fromthe user, and wherein determining the adjustment comprises calculatingthe adjustment to the setting of the at least one ink control deviceusing the modification to the displayed captured image.
 3. The method ofclaim 2, wherein the input data indicates an indirect adjustment to theat least one ink control device, and wherein the adjustment iscalculated using the indirect adjustment from the remote input device.4. The method of claim 3, wherein the input data indicates a change to acolor of a portion of the captured image, and wherein the adjustment iscalculated to implement the change to the color of a correspondingportion of the printed product.
 5. The method of claim 4, wherein theinput data indicates the change to the color in color coordinates withina standardized color space, and wherein the adjustment is calculatedusing the received color coordinates.
 6. The method of claim 1, whereinthe input data represents a direct adjustment to the setting of the atleast one ink control device, and wherein transmitting the controlsignal comprises configuring the control signal to cause the at leastone ink control device to implement the direct adjustment in response toreceiving the control signal.
 7. The method of claim 1, wherein the inkcontrol device comprises an ink key, and wherein transmitting thecontrol signal comprises configuring the control signal to cause the atleast one ink control device to adjust an opening of the ink key toimplement the determined adjustment.
 8. A system comprising: an imagecapturing device configured to generated a captured image of a printedproduct on a printing press; and a circuit communicably connected to theimage capturing device and configured to: transmit the captured image toa display located remote from the image capturing device, receive inputdata from a remote input device indicating input from a user withrespect to the displayed captured image, and transmit a control signalto adjust at least one of a plurality of ink control devices of theprinting press based on the input data received from the remote inputdevice.
 9. The system of claim 8, wherein the input data represents amodification to the displayed captured image received from the user, andwherein the circuit is further configured to calculate an adjustment tothe at least one ink control device to implement the modification on theprinting press.
 10. The system of claim 9, wherein the input dataindicates an indirect adjustment to the at least one ink control device,and wherein the circuit is configured to calculate the adjustment to theat least one ink control device using the indirect adjustment from theremote input device.
 11. The system of claim 10, wherein the input dataindicates a change to a color of a portion of the captured image, andwherein the circuit is configured to calculate the adjustment to the atleast one ink control device to implement the change to the color of acorresponding portion of the printed product.
 12. The system of claim11, wherein the input data indicates the change to the color in colorcoordinates within a standardized color space, and wherein the circuitis configured to calculate the adjustment to the at least one inkcontrol device using the received color coordinates.
 13. The system ofclaim 8, wherein the input data represents a direct adjustment to theink control device, and wherein the control circuit configures thecontrol signal to cause the at least one ink control device to implementthe direct adjustment in response to receiving the control signal. 14.The system of claim 8, wherein the ink control device comprises an inkkey, and wherein the control circuit configures the control signal tocause the at least one ink control device to adjust an opening of theink key to implement the determined adjustment.
 15. A printing presscomprising: a plurality of ink control devices configured to deposit inkonto a substrate to generate a printed image on the substrate; an imagecapturing device configured to generated a captured image of the printedimage on the substrate; and a circuit communicably connected to theimage capturing device and the ink control devices and configured to:transmit the captured image to a display located remote from the imagecapturing device, receive input data from a remote input deviceindicating input from a user with respect to the displayed capturedimage, and transmit a control signal to adjust at least one of theplurality of ink control devices of the printing press based on theinput data received from the remote input device.
 16. The printing pressof claim 15, wherein the input data represents a modification to thedisplayed captured image received from the user, and wherein the circuitis further configured to calculate an adjustment to the at least one inkcontrol device to implement the modification on the printing press. 17.The printing press of claim 16, wherein the input data indicates anindirect adjustment to the at least one ink control device, and whereinthe circuit is configured to calculate the adjustment to the at leastone ink control device using the indirect adjustment from the remoteinput device.
 18. The printing press of claim 17, wherein the input dataindicates a change to a color of a portion of the captured image, andwherein the circuit is configured to calculate the adjustment to the atleast one ink control device to implement the change to the color of acorresponding portion of the printed product.
 19. The printing press ofclaim 18, wherein the input data indicates the change to the color incolor coordinates within a standardized color space, and wherein thecircuit is configured to calculate the adjustment to the at least oneink control device using the received color coordinates.
 20. Theprinting press of claim 15, wherein the input data represents a directadjustment to the ink control device, and wherein the control circuitconfigures the control signal to cause the at least one ink controldevice to implement the direct adjustment in response to receiving thecontrol signal.